Graining machine for zinc offsetprinting plates



w. F. HORST 2,576,088

GRAINING MACHINE FOR ZINC OFFSET-PRINTING PLATES Nov. 27, 1951 Filed sept 14, 195o attorney Y Patented Nov. 27, 1951 UNITED STATES PATENT OFFICE N GRAINING MACHINE FOR ZINC OFFSET- PRINTING PLATES Walter F. Horst, Lubeck, Schleswig-Holstein,

This invention relates to a machine for graining the surfaces of'zinc offset-printing plates and the like.

Conventional graining machines, because of the eccentric or gyrating motion of the massive graining boxes thereof, are necessarily supported on expensive massive frames. Expensive and shortlived gearing or other mechanism is conventionally employed toeffect connection with a prime mover (motor, etc.) and the box-gyrating mechanism. Despitel sturdy fra-mes and strong anchor- `ing supports for these prior machines, it will be realized that they, nevertheless, have considerable vibration which produces a noisy operation and, more important, subjects the machine and the building housing the same to forces deleterious to both the machine and the building.

Accordingly, it is a general object of the present invention to provide a graining machine of the `character referred to that is substantially noiseless and free of vibration; extremely light in Weightcompared to prior machines of comparable size; long-lived because of elimination of wear points of prior machines; and of low upkeep in that wear is minimized and the need forlubrication reduced to a minimum.

Another object of the invention is to provide a graining machine `that is suspended freely from above, thereby eliminating costly supports and anchorages and enabling smooth, vibrationless gyration of the graining box with the abovementioned favorable advantages.

A further object of the invention is to provide a freely` suspended graining machine that can readily be tilted while in operation so that the balls used for graining a plate in the machine can be rolled into a receiving trough to thereby obviate marring of the; plate, an undesired result frequently attending manual removal of the balls.

A still further object of the invention is to provide a graining machine in which the freely suspended graining box mounts both the gyrationinducing means and the prime mover so that none of the movement of the machine is transmitted to the structure housing the same.

The invention also has for its objects to provide such means that are positive in operation, convenient in use, easily installed in a working position and easily disconnected therefrom, economical of manufacture, relatively simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. However, the drawings merely show and the following description merely describes one embodiment of the present invention, which is given by Way of illustration or example only.

In the drawings, like reference characters designate similar parts in the several views.

Fig. 1 is a vertical sectional view of` a plategraining machine according to the present invention, the suspension means thereof being foreshortened.

Fig. 2 is a plan sectional View as taken on line 2-2 of Fig. 1.

In Fig. l the ceiling 5 is intended to represent any overhead structure as of a building, and may be girders below or forming part of an unduly high ceiling. The wall 6 is similarly representative of a suitable laterally disposed support and many be a post,` column, etc.

The present graining machine is shown suspended, in part, from ceiling 5 and, in part, from wall 6, but it will be clear from the following description that said ceiling alone may serve as the sole support for the machine.

The machine that is illustrated comprises, generally, a graining box l, gyration-inducing means 8 afxed to the bottom of said box, a prime mover 9, also affixed to the bottom of the box: and connected to drive the means 8, means III suspending the box from the ceiling 5 alone or from said ceiling and an adjacent wall 6, and means II to adjust the suspension means ID for levelling or tilting the box, as desired.

The graining box I is generally conventional in that it comprises a rectangular tray-like structure formed with a substantially liat bottom I2 and shallow surrounding walls I3. In the usual manner, the box is provided with plate-clamping means that is here shown as a set of clamp screws I4, mounted for adjustment along transverse guides I5, and serving to clamp a plate against the bottom I2. A trough I6 is provided along one side of box 1 to receive graining balls after the same have completed a graining operation on a plate held by clamp screws I4. A ball-intercepting barrier wall I1 is interposed between said trough and the remainder of the box and is adapted to be raised to allow balls to roll from a plate into trough I6. A valve-controlled drain I8 is provided for said trough. Preferably at the four corners of the box there are provided upwardly directed hooks or eyes I9.

The gyration-inducing means 8 is carried on a vertical stud 20 aflixed to the under surface of bottom I2 of the box, a pulley or flywheel or a combined pulley and ywheel 2| rotatonally mounted on stud 20. and a weight 22 eccentrically mounted on pulley 2| and adjustable relatively to the center of said pulley to give the degree of unbalance desired.

The prime mover 9 is shown as an electric motor 23, disposed vertically on a bracket 24 depending from box 1, and a pulley 25 driven by said motor, said pulley being preferably considerably smaller than pulley 2|. A belt 2E connects said pulley. In practice, the prime mover is located near one corner of the box while the means 8 is located ai; the -approximate center thereof, substantially as shown.

The means Hi comprises two chains or cables 21 that connect to hooks I9 on the side of the box that has trough I8 and to hooks or eyes 28 aflixed to the ceiling 5, and two chains or cables 29 that extend from the other two hooks I9, are trained over a pair of sheaves 30 aiiixed to the ceiling, and connect to the means l l. The latter means is 1 in the form of a Winch or hoist thatl is provided Vwith an operating handle 3i which, by manual rotation, takes up or pays out the cables 29 wound on a drum 32. A suitable dog and ratchet 33 is provided to hold the Winch at any point, of adjustment. As Vhereinbefore indicated, the means H may replace pulley 30 on the ceiling, in which case, the handle 3l may be replaced by a con- -ventional hoist control chain.

It will be clear from the foregoing that box l is freely suspended from cables 2l and 28'; `that the unbalanced pulley 2l will set ,up` gyration of tionless; that the free-swinging suspension afforded by the cables;obviates transmission of the f forces involved to the ceiling and that the -machine is light in weight since the same has no heavy framework nor anchors.

The box l will remain level at al1 times since all four cables maintain parallelism, thereby assur- Ving proper and uniform dispersion of the graining iballs during operation. When the balls are to be removed, the same is effectively accomplished by raising or removing barrier wall Il and operating ,handle 3| through a small movement to foreshorten cables 29 to slightly tilt the box in a direction to discharge the balls into trough I 6. l

While the invention that has been illustrated and described is now regarded as the preferred embodiment, the construction is, of course, subject to modifications without departing from the spirit and scope of the invention. Itis, therefore,

not desired to restrict the invention to the particular form of construction illustrated and described, but to cover all modifications that may fall within the scope of the appended claims.

' Having'thus described the invention, what is 4, claimed and desired to be secured by Letters Patent is:

1. A freely suspended and free-swinging graining box, and means entirely carried by the box to gyrate the same, said means comprising an eccentrically weighted rotational member and aV drive for the latter.

- 2. A graining box, cable means freely suspending said box from above, means to adjust the cable means to move the box between a `level and tilted position, and gyration-inducing means entirely carried by and movable with the box, said latter means comprising an eccentrically weighted rotational member and a drive for said member, both aiiixed to vthe bottom of the box.

3. A graining machine comprising a graining box of generally rectangular form, two cables at the corners of one side of the box to suspend the same from above, two cables at the corners of the opposite side of theV box, sheave means above the box over which the latter cables are trained, a hoist connected to the free ends of the latter cables to move the box between a level and a tilted position, and means to'impartl gyrating movement to the box so suspended, said means being` carried by the box and movable therewith.

Y 4. A graining box, means freely suspending said box from above, a prime mover mounted on the box, and an eccentrically Weighted rotational member also mounted on the box anddriven by the prime mover, said prime mover and rotational member constituting means to gyrate the freely suspended box, and said means gyrating with the box.

5. A device according to claim4, in which the box is provided with a bottom, and the prime mover and rotational member are mounted on said bottom below the box.

6. A device according to claime, in which the box is rectangular and is provided with a bottom, the rotational member being mounted substantially at the center of saidV bottom andthe prime mover mounted adjacent one corner. of said bottom, both the rotational member and prime mover depending from the box bottom. v

WALTER F. HORST.A

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS l Date 

